STAT3 and cancer: Leptin targets the Ob-R/LEPR receptor on the cancer cell surface to enhance the expression of PLOD2 and activates signaling pathways, such as JAK/STAT3 and PI3K/AKT signaling pathways, as well as the adipocyte-derived IL-6.Leptin contributes to the maintenance of androgen phenotype in BC, the cancer cell proliferation, and the EMT in ovarian cancer cells.